awake transnasal laser-assisted surgery (tnls) and microlaryngeal surgery for vocal cord cyst

Conditions: Vocal Cord Cyst

Summary: this is a prospective randomised controlled trial conducted at two tertiary referral hospitals in hong kong to compare the clinical and functional outcomes of office-based awake transnasal laser-assisted laryngeal surgery (tnls) under local anesthesia to traditional microlaryngeal surgery for vocal cord cyst under general anesthesia.

the aim of the study is to prospectively compare the functional and clinical outcomes of tnls under local anesthesia and mls under general anesthesia in managing vocal cord cysts. office-based awake transnasal laser-assisted surgery (tnls) has been gaining popularity in treating different laryngeal lesions, with the advantages of avoiding general anesthetic risks and minimizing healthcare-related costs. in addition, the general waiting time for surgeries under general anesthesia in public hospitals is getting longer due to the increasing population and limited resources. the investigators have recently conducted a novel randomized controlled trial in 2021-2022 comparing the functional and cost-effectiveness of traditional microlaryngeal surgery (mls) under general anesthesia and tnls for benign laryngeal lesions (vocal cord polyps, nodules, cysts, granuloma and reinke's edema), and found that tnls was superior to mls in terms of length of stay, intraoperative complications, perioperative throat discomfort and hospital costs; while it was equivalent to mls in terms of functional outcome, operative time and recurrence rate. however, since the previous study's main goal was to compare tnls to mls in a macroscopic perspective in terms of functional outcomes and cost-effectiveness, it had included a wide variety of benign laryngeal lesions, and different vocal cord lesions may respond differently to laser surgery. vocal cord cyst is a fluid-filled sac inside the vocal cord, with 2 subtypes: 1) epidermoid cyst due to epithelial inclusion 2) mucous retention cyst due to glandular ductal obstruction. vocal cord cysts typically do not resolve with voice therapy, and are traditionally excised with microlaryngeal surgery with microflap technique or marsupialization. in our previous rct study, subgroup analysis did not show a significant difference of vocal cord cyst recurrence in both tnls and mls group. however, the investigators' cohort had a higher overall vocal cord cyst recurrence rate (13.8%) compared to historic cohort rate of 2.2-8.7% , which may be accounted by that the vocal cord cysts were ablated and marsupialized instead of removed in the tnls group. nevertheless, a recent case series by gao and colleagues showed a good functional outcome of awake ktp-laser marsupialization in selected cases. a larger cohort is warranted to compare tnls to mls for vocal cord cyst. therefore, the investigators would like to conduct a randomized controlled trial to compared tradition mls surgery to tnls, with hypothesis that tnls would be non-inferior to traditional microlaryngeal surgery in benign laryngeal lesions, and with its additional benefits on minimization of anesthetic risks and hospital expenses, hopefully to expand its further application.

Eligibility criteria:
inclusion criteria: * patients with vocal cord cysts * older than 18-year-old * able to independently provide consent * able to tolerate flexible laryngoscopy would be recruited exclusion criteria: * under 18-year-old * unable to independently give an informed consent * unable to tolerate flexible laryngoscopy * allergic to local anesthesia * had unfavorable anatomy such as prolapsing epiglottis precluding adequate visualization, extensive lesions and an expected difficult operation as judged by the surgeons * with pathologies other than vocal cord cyst

Keywords: vocal cord cyst transnasal laser surgery microlaryngeal surgery office based laser surgery awake laser laryngeal surgery trublue laser